Its a good question. I have both the OF1400 and the Domino. Here's how I generally divide up the work:
If its a one-off project with no huge structural needs (e.g. exterior door, workbench), curves or compound angles, definitely a Domino. No brainer.
In my opinion, the Domino lacks an effective clamping mechanism for complex joinery. If you need to make several mortises at compound angles, making a router jig will save time. Ditto for curved work.
I love Pete's jig, but my technique is much simpler. Make a simple jig and toss it when you finish the project. Here are some hints:
Use your OF1400 (or other router) on a guide rail. Put a 1/2 inch bit in it and plow a through slot into 1/4 inch MDF. More on calculating length in a second. This slot will guide a 1/2 outside diameter guide bushing (Festool calls them copy rings) that you place in your OF1400 when you are ready to mortise. I usually make 3/8 thick mortises (3/8 inch collet and a 3/8 inch endmill) so I need to make the slot in the mdf a little long to accomodate the final length of the mortise. The extra length is simply the difference between the 1/2 od on the guide bushing and the 3/8 inch diameter of the end mill or router bit (1/2-3/8 = 1/8) so make it 1/8 longer on each end of the mortise. This formula works for any size bit, just be sure there is clearance between the bit and the inside of the bushing. OK, end of math.
You can use stops on your rail to cut the grooves accurately to length.
Now the beauty part, once you have the setup, make a bunch of these in often used lengths. I space about 6 inches between grooves. Most of your work is done for a few years and you have spent a few $ on 1/4 mdf.
Now use a pencil and a good ruler to lay out a mortise on a workpiece (or scrap). You can lay a grooved mdf over the layout and align with your eyeballs. Clamp it to the workpiece. Find a piece of hardwood scrap, maybe 3/4 thick, couple of inches wide and 6 or so inches longer (maybe more). Place it against the workpiece, under the mdf. I just shoot a few pins through the mdf and into the scrap. Now you have a fence.
When ready to route, clamp the fence, run the router with the guide bushing in the mdf slot and you are done.
For extra credit, make the jig so that it will register against a key reference on the workpiece, say top of the table leg and top of the apron. If you have curved stock, draw the curve on fence scrap, bandsaw, smooth, and go on from there as usual.
Extremely versatile, costs next to nothing and very accurate. I use these to make chairs which have compound angles on curved surfaces. Without a curve and with the slots already in the MDF, I can make one in about 15 minutes, mostly spent on laying out the first mortise on the workpiece.
OF-FH 2200
